A System of Instruction in the Practical Use of the Blowpipe: Being A Graduated Course Of Analysis For The Use Of Students And All Those Engaged In The Examination Of Metallic Combinations — John Shaqi
A System of Instruction in the Practical Use of the Blowpipe: Being A Graduated Course Of Analysis For The Use Of Students And All Those Engaged In The Examination Of Metallic CombinationsAnonymous
Science
A System of Instruction in the Practical Use of the Blowpipe: Being A Graduated Course Of Analysis For The Use Of Students And All Those Engaged In The Examination Of Metallic Combinations
Anonymous
Blowpipe
Sulphide of lithium, formed by heating the sulphate in the reducing
flame, is volatilized in similar manner by a strong blast, although
less readily than the sulphide of sodium. It affords a greyish white
film, which disappears with a crimson flame when submitted to the
reducing flame.
Besides the above, the sulphides of bismuth and lead give, when heated
in either flame, two different incrustations, of which the more
volatile is of a white color, and consists in the one case of sulphate
of lead, and in the other of sulphate of bismuth. If either of these
be heated under the reducing flame, it disappears in the former case
with a bluish flame, in the latter unaccompanied by any visible flame.
The incrustation formed nearest to the assay consists of the oxide of
lead or bismuth, and is easily recognized by its color when hot and
after cooling. There are many other metallic sulphides, which, when
heated by the blowpipe flame, cover the charcoal with a white
incrustation, as sulphide of antimony, sulphide of zinc, and sulphide
of tin. In all these cases, however, the incrustation consists of the
metallic oxide alone, and either volatilizes or remains unchanged,
when submitted to the oxidizing flame.
Of the metallic chlorides there are many which, when heated on
charcoal with the blowpipe flame, are volatilized and redeposited as a
white incrustation. Among these are the chlorides of potassium,
sodium, and lithium, which volatilize and cover the charcoal
immediately around the assay with a thin white film, after they have
been fused and absorbed into the charcoal, chloride of potassium forms
the thickest deposit, and chloride of lithium the thinnest, the
latter being moreover of a greyish-white color. The chlorides of
ammonium, mercury, and antimony volatilize without fusing.
The chlorides of zinc, cadmium, lead, bismuth, and tin first fuse and
then cover the charcoal with two different incrustations, one of which
is a white volatile chloride, and the other a less volatile oxide of
the metal.
Some of the incrustations formed by metallic chlorides disappear with
a colored flame when heated with the reducing flame; thus chloride of
potassium affords a violet flame, chloride of sodium an orange one,
chloride of lithium a crimson flame, and chloride of lead a blue one.
The other metals mentioned above volatilize without coloring the
flame.
The chloride of copper fuses and colors the flame of a beautiful blue.
Moreover, if a continuous blast be directed upon the salt, a part of
it is driven off in the form of white fumes which smell strongly of
chlorine, and the charcoal is covered with incrustations of three
different colors. That which is formed nearest to the assay is of a
dark grey color, the next, a dark yellow passing into brown, and the
most distant of a bluish white color. If this incrustation be heated
under the reducing flame, it disappears with a blue flame.
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